Roof supports for mine workings



Sept. 16, 1969 K. M. GROETSCHEL ROOF SUPPORTS FOR MINE WORKINGS Original Filed April 21. 1966 7 Sheets-Sheet l lnvan'l'cr: KwL Maurie. ivoeb h Sept. 16, 1969 K. M. GROETSCHEL ROOF SUPPORTS FOR MINE WORKINGS Original Filed April 21. 1966 7 Sheets-Sheet 2 n M H 3 1 H 1 W T .v. .a m. fi T, n mv l fihwmmmwwwm mm m m n m 2 I QM 3a---- l i I l l| llll 1? 0 0000 n wwwwvuwwmr q Sept. 16, 1969 K. M. GROETSCHEL 3,466,375

ROOF SUPPORTS FOR MINE WORKINGS Original Filed April 21. 1966 7 Sheets-Sheet 5 m K v a:

Sept. 16, 1969 K. M. GROETSCHEL 3,466,375

ROOF SUPPORTS FOR MINE WORKINGS Original Filed April 21. 1966 "r Sheets-Sheet 4 I49 I58 HS I57 I48 I59 I60 IIZ \nvenkr: Karl Mari-o. G' Z' fir E Sept. 16, 1969 K. M. GROETSCHEL.

ROOF SUPPORTS FOR MINE WORKINGS Original Filed April 21. 1966 7 Sheets-Sheet 6 lnvcntonb L Kart mam, Gvoekac a.

fin Em QM WC fitter awn 9m mm own win Sept. 16, 1969 K. M. GROETSCHEL 3,465,875

ROOF SUPPORTS FOR MINE WORKINGS Original Filed April 21, 1966 7 Sheets-Sheet '7 ass 5 o 572 S48 \nverdor: Kart Mario. GvoetsalzaL a ar -G M Q 4! as wo hau j United States Patent Int. Cl. 1521a 11/00 US. C]. 61-45 21 Claims ABSTRACT OF THE DISCLOSURE This invention relates to a roof support for a mine working in which a superstructure carried on the upper end of props mounted on a base is formed in two parts of which the first comprises laterally spaced longitudinally extending roof bars connected by laterally extending cross members and defining a channel in which the second part of the superstructure, which is in the form of a beam, is disposed. The beam incorporates a downwardly presented bearing surface beneath which is disposed a prop equipped with a shoe to allow the beam to be moved slidably relatively to the prop by a hydraulic traction ram incorporated in the superstructure. The beam is also supported additionally to the prop by a cradle structure disposed beneath the beam forwardly of the prop and supported by strut elements inclining upwardly and forwardly from the base of the support.

CROSS REFERENCES TO RELATED APPLICATIONS This invention is a division from my pending application Ser. No. 544,145 filed on Apr. 21, 1966, now Paten No. 3,399,927.

BACKGROUND OF THE INVENTION Field of the invention This invention relates to a method of and apparatus for supporting the roof of an underground mine working.

The invention has been developed primarily in relation to the support of the roof of an underground coal mine working of the form encountered when coal is mined by the method of long wall coal mining.

In this method a coal winning machine is traversed along a coal face and coal thus removed from the face is discharged or deflected on to a conveyor which extends along the coal face, and which includes a trackway along which the coal winning machine is moved under power.

The roof of the mine working extending over the top of the coal winning machine and in a direction away from the coal face and includes the portion which is newly exposed as the coal winning machine cuts the coal away from the face, requires to be supported.

In many mine workings the condition of the strata immediately adjacent to the roof is such that falls of roof material cannot entirely be prevented by the installation of roof supports at intervals along the coal face. Falls of roof material may occur in between such supports and may cause injury to personnel and possibly damage to equipment operating in this region.

In my pending application Ser. No. 544,145 filed on Apr. 21, 1966, I have disclosed and claimed a method of supporting an underground mine working comprising stationing, beneath said roof, a flexible mat having a stored portion and an extended portion leading off from said stored portion, supporting said extended portion at an elevated position adjacent to said roof, holding said elevated portion stationary while moving said stored portion along a path therebeneath to withdraw a further 3,466,875 Patented Sept. 16, 1969 length of said mat from said stored portion and increasmg the length of said extended portion, and underpinning said extended portion of said mat at intervals along its length by prop supported superstructure.

In a preferred manner of carrying out this method where the roof to be supported is newly exposed by the passage of a winning machine along an upright face of the working, said stored portion of the mat is disposed ad acent to said winning machine and is moved in c0- ordlnation therewith along said face, said extended port1on is held in a position to underlie said newly exposed roof, and underpinning of said extended portion is effected by cantilever elements moved into a position beneath said extended portion, and supporting said elements by props offset rearwardly from said extended portion of said mat.

The early underpinning of the extended portion of th mat s of importance. Under certain conditions of operation in mine workings it is also important to provide early support to a newly exposed roof where no mat is utilised.

Description of the prior art Heretofore one of the limitations which has existed in providing such early support has been that it has been contmgent upon being able to advance at least that part of the base which carries the prop for supporting the fore part of the superstructure.

Where the base is a single base element the whole of the base has to be advanced for this purpose, and this requires that the conveyor, normally situated adjacent the coal face, should be pushed towards the newly exposed coal face and the base then drawn up to the conveyor in its new position by the traction means, normally a hydraulic ram provided in the base. If the base comprises two base elements operatively connected by a traction means, such as a hydraulic ram, there must be sufiicient space in front of the forward base element between this and the conveyor to permit of advancement of this base element. This again normally requires that the conveyor itself should be advanced towards the newly exposed coal face before any advancement of the forward base element can take place.

The object of the present invention is to provide a new or improved form of self-advancing roof support which may be employed in the method of the invention or as part of the apparatus hereinbefore described to overcome or avoid this problem, but which may also be independently employed for supporting the roof especially wher it is of importance to provide early support to a newly exposed roof even if no mat should be utilised.

SUMMARY OF THE INVENTION With this object in view and from a further aspect th invention resides in the provision of a self-advancing roof support for supporting the roof of a mine working comprising a base, a plurality of power-operated extensible props mounted on said base, a roof engaging superstructure carried by said props at their upper ends, said superstructure including a first part comprising laterally spaced longitudinally extending roof bars connected by laterally extending channel presenting an open end forwardly, said superstructure further including a second part comprising an elongated beam having its rear portion disposed in said channel and its forward portion projecting forwardly beyond said base and supported by one of said props thereon, an auxiliary means for urging upwardly at least the portion of said beam situated forwardly of the supporting prop therefor, and traction means including a part operative at the level of said superstructure for advancing said beam relatively to said rear part of the superstructure.

3 BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a view in side elevation showing one embodiment of apparatus in accordance with the invention for carrying out the method thereof.

FIGURE 2 is a plan view of the embodiment shown in FIGURE 1.

FIGURE 3 is a fragmentary view in side elevation partly in vertical cross section illustrating a modification of the forward end portion of the beam which forms the fore part of the superstructure.

FIGURE 4 is a view in side elevation of one form of a second embodiment of self-advancing roof support which may be part of the apparatus shown in FIGURES 1 and 2 in substitution for the self-advancing roof support therein shown.

FIGURE 5 is a plan view of the second embodiment of the self-advancing roof support.

FIGURE 6 is a fragmentary view in end elevation and partly in cross section showing a modification of the guide means of FIGURES 4 and 5 operative between the rearward end of the beam which forms the fore part of the superstructure and the roof bars which form the rear part of the superstructure.

FIGURE 7 is a view corresponding to FIGURE 1 of a third embodiment of self-advancing roof support forming part of an apparatus for performing the method.

FIGURE 8 is a plan view of the embodiment shown in FIGURE 7.

FIGURE 9 is a view corresponding to FIGURE 1 of a fourth embodiment of self-advancing roof support forming part of an apparatus for performing the method of the invention.

FIGURES l0 and 11 are fragmentary views in side elevation and plan showing a modification of the fourth embodiment.

Referring to FIGURES 1 and 2 the apparatus thereshown is intended to be utilised for performing the method of supporting the roof in accordance with the invention in a mine working, for example a coal mine, in which the coal is extracted by the method of long wall coal minmg.

In this method of coal mining coal is cut by a coal winning machine having a cutter (not shown) to form an upright coal face 11, and the coal winning machine is traversed along a trackway 12 forming part of a conveyor 13 extending for the length of the coal face which may typically be 200 yards long. Movement of the coal winning machine 10 is effected by power operated means, for example endless driving chains extending along the trackway of a conveyor.

The coal winning machine normally includes or is associated with a deflector means or plough for deflecting I the drum or coil may be carried by the gibs 17 in such coal cut from the face on to the deck plate 14 of the conveyor.

The portion of the roof newly exposed by passage of the coal winning machine is indicated at 15 and the apparatus now described provides support for this newly exposed portion of the roof on the training side of the coal winning machine.

For this purpose the apparatus comprises a means for storing a portion of a mat hereinafter described in more detail. Such means may comprise an arm in the form of a spindle 16 extending horizontally towards the coal face a:

The spindle 16 may be of substantial diameter so that the coiled or stored portion of the mat can be supported directly thereon in a manner permitting of rotation of the coil on the spindle, or alternatively the coiled portion of the mat may be wound on to a drum which is rotatably I supported on the spindle 16. 7 Although not illustrated the spindle 16 together with a manner as to permit of axial adjustment of the sipndle to position the coil nearer to or further from the coal face 11 as desired.

As a possible alternative to providing a spindle on which a mat in coiled form is rotatable, the means for storing the mat could be in the form of a container. In this case the stored portion of the mat may be either in the form .of a coil or the mat could be folded concertinawise in the container.

.In any of the foregoing cases a portion of the mat adjacent to its free end can be led off from the coil or folded stored portion. The portion which is led off in this case is herein referred to as the extended portion of the mat. The coiled stored portion of the mat is indicated at 18 and the extended portion at 19 including the extended portions applied in preceding traverses. The extended portions applied in preceding traverses may be connected to' each other by cables or other fastening means. The extended portion is maintained at an elevated position in contact with the roof by a support means comprising a roller 20 journalled for rotation about a horizontal axis on a spindle 21 which is, in turn, carried by a yoke 22 at the upper end of a post 23. The post 23 may be of rectangular cross section and may be vertically adjustable "in a guide opening of corresponding cross sectional shape formed adjacent to the forward end of an arm 24 projecting forwardly from the body part 25 to which it is secured.

The roller 20 may be urged upwardly towards the roof by a leaf spring 26 projecting forwardly from a mounting block 27 on top of the body part 25 and secured thereto as a cantilever, the forward end of the spring being bifurcated to engage around the post 23 beneath the yoke 22.

The roller 20 can be mounted on the spindle 21 for free rotation thereon but is preferably subjected to a braking torque by means of a brake device.

The mat itself, as seen particularly in FIGURE 2, may be a mesh structure composed of elongated filamentary elements maintained in the desired positional relationship to each other by virtue of a woven relationship, that is to say each element passes alternatively above and be low those which extend transversely to it.

Whilst it is convenient to employ a single roller, such as 29 to apply on such mats more than one such roller could be provided if desired.

Referring now to the form of self-advancing roof support illustrated in FIGURES 1 and 2, this comprises ward ends, in the former of which are disposed two later- -ally spaced props 38 and in the latter of which is accomniodated a single multi-section prop 39. These props are hydraulic props which can be extended by admission of 'hydraulicfluid'to the chamber of the prop or each chamber in the case of the multi-section prop, such fluid being derived from a power-operated pump or possibly a manually or foot-operated pump.

Reference herein to power-operated props is to be deemed to include manual or foot operation of the pump.

The multi-section prop 39 includes an inner prop unit 40 and anouter prop unit 41.

'The outer prop unit 41 carries at its upper end a generally oval frame-like yoke, lateral extremities of which are provided with upwardly projecting posts 43 and carried on these posts and on the two rearward props 38 is the rearpart ofa superstructure indicated generally at 44.

The first part of the superstructure, herein called the rear part/is in the form of a frame including laterally spaced, longitudinally extending, roof bars 45. These roof bars may be either of single box section or, as illustrated,

formed of two box section girders welded together along laterally projecting flanges which are continuations of their upper and lower horizontal webs. The roof bars 45 are connected at their rearward ends by a downwardly cranked cross member 46 also of box section and at their forward ends by a similar downwardly cranked box section cross member 47.

The superstructure further comprises a second part herein called the fore part, in the form of a long beam 48. This comprises laterally spaced roof bars 49 also of box section connected at intervals along their length by cross members 50, 51, 52. The long beam 48 has its rear portion disposed in the upwardly presented channel defined by the roof bars and cross members of the rear part of the superstructure, such channel being open at the forward end by virtue of the downwardly cranked form of the cross member 47, thereby allowing the forward portion of the long beam to project forwardly beyond the base element and into a region above the coal winning machine.

The long beam 48 is supported from the inner prop unit of the multi-section prop 39 through the intermediary of a shoe 53 which engages the downwardly presented surface of a plate 54 welded or otherwise secured to the roof bars 49 of which the longer beam is formed. Such plate 54 is at one end connected to the cross member 51 and at the opposite end to an apertured block 55 through which extends the piston rod 56 of a double-acting hydraulic ram 58, the cylinder 57 whereof is pivotally connected to the cross member 52 about a horizontal axis transverse to the length of the long beam. The stroke of the rams 58 and 59 may be equal to each other and correspond to the advancement stop to be made for each traverse of the coal winning machine. The ram 58 may have an effective diameter less than that of the inner prop unit 40. The setting load exerted by the latter would then be decreased during advancement of the long beam member by the ram 58. Alternatively the effective diameter of the ram 58 may be increased if necessary beyond that of prop unit 40 to permit of advancement of beam 48 under a full value of setting load exerted by prop unit 40.

The double-acting hydraulic ram 58 forms the upper part of traction means, the lower part of which comprises a pair of double-acting hydraulic rams mounted in the base element 35, one of these being seen at 59 and having its piston rod 60 provided with a forked termination for pivotal connection at 61 to a bracket on the trackway 12 of the conveyor 13.

At its rearward end the long beam 48 is provided with a box section member 62 of internal dimensions to receive the rear end portion of the long beam. Such box sec tion member has laterally projecting arms 63 and its side walls are formed with horizontal, longitudinally extending, slots 64 in which engage a horizontal transverse pin 65 secured to, and projecting laterally from, the long beam. The member 64 can thus slide relatively to the long beam between limits determined by engagement between the pins 65 and the ends of the slots 64. The internal dimensions of the member 64 are such that there is little or no free lateral or upward and downward movement between this member and the long beam but sliding movement can take place easily.

The member 22 can be moved slidably relatively to the long beam by means of a double-acting hydraulic ram 66 the piston rod 68 of which is pivotally connected to a medial lug 67 projecting downwardly from the top wall of the member 22 and the cylinder 69 whereof is pivotally connected about a horizontal axis to the cross member 51. Initially the member 22 may be held back by frictional engagement with the roof during advancement of the long beam 48 and thereafter drawn forwardly of the ram 66.

The arms 63 of the member 62 are equipped, adjacent to their outer ends, with relatively short hydraulic piston and cylinder units 70, the cylinders whereof are secured to the arms at their undersides and the piston rods or plungers whereof, as indicated at 71, project upwardly through the apertures in the arms 63 to engage contact surfaces presented downwardly at the undersides of the roof bars 45. The units 70 may be connected hydraulically with the ram 58, so as to enable the rearward end of the beam to be depressed automatically during its advancement by the ram 58 and thereby increase the support applied in the forward zone of the roof.

Forwardly of the inner prop unit 40 and associated shoe 53, the long beam 48 is further supported by a carrier means underlying the long beam in the form of a cross member 72 having an upwardly presented face engaging contact faces at the undersides of the two roof bars 49 and itself carried by cantilever arms 73 secured to the cross member 33 and to a downward connection 74 at the forward end of each roof bar 45 of the rear part of the superstructure. The cantilever arms 73 are preferably formed as leaf springs of a material such as spring steel and with the parts in the position shown in FIGURE 1 are stressed so that the cross member 72 exerts an upthrust or preload against the underside of the long beam 48.

In utilising the apparatus to carry out the method of roof support, the coal winning machine will be disposed initially at one end of the trackway 12 of the conveyor 13. The extended portion 19 of the mat is passed above the roller 26 and is suitably secured to an anchorage adjacent the roof, for example by being clamped thereagainst by the long beam 48 of the self-advancing roof support situated on the trailing side of the coal winning machine.

As the coal winning machine moves along the coal face by the power-operated driving means provided on the conveyor 13, coal is cut from the coal face and a portion of the roof is newly exposed as indicated at 15.

The mat is unwound from the stored portion on the spindle l6 and, due to the operation of the brake device 28 acting on the roller 20, the mat is not only applied against the roof by the roller 20 but is maintained in a state of tension so that it lies closely against the roof and does not sag.

As soon as the roller 20 has passed each self-advancing roof support the long beam of the latter is advanced by appropriate pressurisation by hydraulic fluid of the ram 58 to extend the ram into the position shown in FIG- URE l in full lines. The initial non-advanced position of the long beam is indicated in FIGURE 1 in chain lineS.

During such advancement the inner prop unit 40 may be depressurised partly or wholly and upthrust applied to the long beam is then derived from the cross member 72 and springs 73. Further upthrust may be derived by pressurisation of the piston and cylinder units 70, the plungers of which, when extended, depress the rearward end of the long beam and cause the forward end to tilt upwardly about a transverse horizontal axis defined by engagement between the shoe 53 and the head of the prop unit 40.

This arrangement permits selected preload to be exerted against the underside of the mat by the long beam during sliding engagement of the latter and moving into a position in which it underpins the mat. When it has been moved into its advanced position, as shown in FIG- URE l, the long beam can be repressurised to the full seating value.

When the coal winning machine and apparatus carried thereby has moved sufiiciently far beyond the self-advancing roof support to permit advancement of the conveyor 13, the latter being composed of articulately connected sections to be soaked or displaced towards the newly exposed coal face, this is effected by pressurisation of the rams 59 to extend their piston rods.

Subsequently the outer prop unit 41 and the rear props 38 are pressurised and the rear part of the superstructure lowered and the rams 59 again pressurised to draw the base and rear part of its support up to the new position of the conveyor section concerned preparatory to repressurising these props and the outer prop unit.

If desired long beam 48 may be equipped with an extension piece preferably of T shape in plan having its narrower stem portion 76 between the roof bars 49 and resting on the upper edge face of the cross member 53. The plate 75 may be supported by leaf spring assemblies 77 engaged slidably in the interiors of the roof bars 49. The plate 75 can be used for supporting part of the roof exposed by a scarped fall of material from the face as shown in chain lines in FIGURE 1.

The plate 75 may be advanced manually if desired. Hydraulic rams may be provided in the interiors of the roof bars 49 and the piston rods 79 being connected to the rearward ends of the leaf springs 77. These rams may be single-acting to produce extensions which are returned subsequently when the long beam as a whole is advanced. Alternatively, double-acting rams may be utilised.

In the modification illustrated in FIGURE 3 the traction ram 58 is replaced by an adjustable length strut 80 having telescopically assembled components 81 and 82 capable of being secured in any of a plurality of relative positions varying the effective length of the strut, as for example by the provision of holes 83 in one of these components, and a cross pin insertable through any of the selected holes 83, and an aligned hole in the component 81. In this case advancement of the long beam to underpin the mat would be deferred until the coal winning had moved beyond the self-advancing roof support sufficiently to permit the adjacent conveyor section to be displaced or snaked towards the coal face and the support as a whole to be drawn up after depressurisation of both the multi-section prop 39 and the rearward props 38, support being then furnished by the cross member 72 and spring 73 acting on the underside of the long beam and by any selected pressurisation of the piston and cylinder units 70.

A plate 84 may be mounted for universal pivotal movement at the forward end of the long beam to provide for application of preload to a selected roof area corresponding to that of the plate 84 while the beam itself bears hollow with respect to the roof. In the hollow bearing zone forepoling arm may provide support as described with reference to FIGURES 4 and 5. Instead of providing the plate 85 the beam 48 may be curved upwardly adjacent to its forward end.

In the construction of self-advancing roof supports illustrated in FIGURES 4, 5 and 6 parts corresponding to those already described in the self-advancing roof supn port illustrated in FIGURES 1 and 2 are designated by like numerals with the prefix 1 and the preceding description is deemed to be applicable thereto. Reference, therefore, will be made only to the modified features of construction.

In this form of roof support the cross member 172, instead of being supported by spring arms, is supported by a strut member 185. The strut member is preferably of telescopic form including an outer element 186 pivotally connected to a bracket 187 on the base element and an inner element 188 pivotally connected to a bracket at the underside of the cross member 172. A clamping device in the form of a screw 189 operating through a collar 190 at the upper end of the element 186 bears directly through the intermediary of a shoe against the inner element 188 to secure it against sliding movement. The inner element may be a hydraulic ram or it may be a rigid inextensible part such as a tubular member. The outer element may comprise a leaf spring assembly providing for yieldable lateral movement of the inner element.

Forward movement of the cross member 172 during advancement of the long beam 148 is prevented by tie members 191 which may be in the form of rods Or a cable secured to the cross member 172 and passing round the inner prop unit or otherwise secured to the rear part of the superstructure.

The cross member itself 172 is provided at its lateral extremities with upwardly projecting lugs 191 which present inwardly facing guide surfaces contacting the outer sides of the long beam.

At its rearward end the long beam 148 is guided laterally in the channel afforded between the roof bars of the rear part of the superstructure by means of laterally projecting guide elements 192. These comprise plungers contained in openings formed in the rearward end portions of the roof bars 149 and urged outwardly by a coiled compression springs 193 disposed between the inner ends of the plungers and supported by an apertured bracket 194. Alternatively as shown in FIGURE 6 a single plunger 192 passing through a transverse opening in the long beam is equipped with a clamp bolt 192i) projecting through a slot 192a in a cross member of the beam and provides for rigid guiding of the beam with the possibility of lateral adjustment.

The plunger or plungers maintain the rearward end of the long beam in a selected lateral position in the channel and prevent any, or any excessive, lateral deflection thereof when the roof support is used in mine workings in which the floor and roof slope in the direction longitudinally of the coal face. The heads of the plunger or plungers contact inwardly presented side faces of the roof bars 145. These faces are bounded at the top and bottom of flanges which limit vertical movement of the plunger heads and hence vertical movement of the rear end of the beam. They are deep enough however to provide the requisite degree of vertical movement for maintaining contact and upward preload between the forward end of the beam and the mat 0r roof. As a further alternative the plungers or the single plunger may be operated by hydraulic piston and cylinder units.

The rear part of the superstructure is further provided in this construction with forepoling arms 195 pivot ally connected about horizontal axes to the enlargements 174 of the roof bars 145 of the rea part of the superstructure and raised and lowered by wedge mechanisms operated by a hydraulically energised piston and cylinder unit (omitted for the sake of clarity from the drawings).

At its rearward end the long beam is further supported by an auxiliary prop 196 which is suspended from the rearward end of the long beam during advancement of the latter, as disclosed in my co-pending application No. 511,511 to which reference may be had for further particulars. The base element 135 is slotted to accommodate the lower end of this prop and a separate floor-engaging element 197 therefor.

In the construction of self-advancing roof support illustrated in FIGURES 7 and 8 parts corresponding to those already described are designated by like numerals of reference with the prefix 2 and the preceding description is to be deemed to be applicable thereto. Reference, therefore, will be made only to the modified features of construction.

In this form of self-advancing roof support the base comprises separate rearward and forward base elements 235a, 235b, the former supporting the two rearward props 238 and the outer prop section 241 of the multi-section prop, the inner prop unit 240 whereof is removed and accommodated in the forward base element 235. A forward extension of the enlargement 274 engages the rearward side of the inner prop unit to stabilise this against rearward deflection during advancement of the long beam 248 by rams 258. The inner prop unit 240 may advantageously be provided with a booster device comprising a short piston and cylinder unit of larger effective diameter than the inner prop unit and having a hollow piston in which the lower end of this unit is received as shown.

The traction rams 259 in the base element 235 serve to connect this with the forward base element 235b.

Auxiliary preload in the long beam, at a position forwardly of the inner prop unit 240, is provided by a cross member 272 supported by cantilever arms 273 each composed of a plurality of leaf springs.

A single piston and cylinder unit 270 is provided adjacent to the rearward end of the long beam, the cylinder of such unit being secured between the roof bars 249 of the long beam 248 and the plunger extending downwardly and being connected centrally to the laterally projecting arms 263, the outer end portions of which operate in guideways 263a defined between the roof bars 245 at the rear part of the superstructure and guide brackets 245a secured to the undersides of the latter in downwardly spaced relation thereto.

Referring now to the embodiment of self-advancing roof support shown in FIGURE 9, parts corresponding to those already described are designated by like numerals of reference with the prefix 3, and the preceding description is to be deemed to be applicable thereto. Reference, therefore, will be made only to the modified features of construction.

In this construction support for the long beam 348 forwardly of the inner prop unit 340 is provided by a cross member 372 underlying the main beam and carried by a pair of rigid arms 398 pivotally connected at 39? at their rearward ends to the rear part of the superstructure. These arms are themselves further supported by strut members 400 preferably in the form of hydraulic rams extending downwardly and rearwardly from points of pivotal connection 401 to the arms, and pivotally connected at their lower ends to brackets 402 on the rear base element 335a. If desired further support to the cross member 372 may be provided by a laminated leaf spring assembly 373 secured as a cantilever to the enlargement 372 at the forward end of each roof bar 345 of the rear part of the superstructure.

Alternatively the strut members 400 can each comprise the combination of hydraulic rams and support elements such as the leaf spring assembly 186 shown in FIGURE 4.

FIGURES l and 11 illustrate a modification of the self-advancing roof support of FIGURES 7 and 8 which may be made to incorporate supporting structure for the cross member underlying the long beam similar to that provided in the embodiment of FIGURES 4 and 5.

Parts corresponding to those already described are designated by like numerals of reference with the prefix 5 and the preceding description is to be deemed to be applied thereto.

In this construction the carrier means instead of comprising a single cross member comprises separate shoes 572a and 57217 anchored against forward movement by rods or cables 599 and supported by telescopic struts 585. Such struts have clamping mechanism 589 for retaining the outer element 586 and the inner element 588 in any selected position of adjustment.

In operating the supports illustrated in FIGURES 7 to 10 the long beam is advanced under preload to underpin the mat while both base elements remain stationary. The forward base element and the inner prop unit carrier thereby is then advanced with the latter partly or wholly depressurised. The hydraulic rams incorporated in the struts 400 may be pressurized as may also the piston and cylinder unit 270 to cause the forward end of the beam to exert preload against the roof at this stage. The inner prop unit is then again pressurised up to its full setting load value. The prop units supporting the rear part of the superstructure are then depressurised and the rear base element drawn forwardly by the rams provided thereon, preparatory to repressurising these prop units to their full setting loads.

In any of the foregoing constructions piston and cylinder units 70, and 270 may be used to assist or accelerate lowering of the rear part of the superstructure to reduce the overall time for a complete sequence of operation.

What I claim then is:

1. A self-advancing roof support for supporting the roof of a mine Working comprising:

(A) a base,

(B) a plurality of power-operated extensible props mounted on said base,

(C) a roof engaging superstructure carried by said props at their upper ends,

(D) said superstructure including a first part comprising laterally spaced longitudinally extending roof bars connected by laterally extending cross members and defining therewith an open ended channel presenting an open end forwardly,

(E) said superstructure further including a second part comprising an elongated beam having its rear portion disposed in said channel and its forward portion projecting forwardly beyond said base and supported by one of said props thereon,

(F) an auxiliary means for urging upwardly at least the portion of said beam situated forwardly of the supporting prop therefor,

(G) and traction means including a part operative at the level of said superstructure for advancing said beam relatively to said rear part of the superstructure.

2. A roof support according to claim 1 wherein:

(A) said axuiliary means comprises carrier means underlying said beam forwardly of its supporting prop, and

(B) means for applying an upward pre-load to said carrier means.

3. A roof support according to claim 2 wherein said means for applying said upward pre-load comprises a spring member supported from said first part of said superstructure and extending forwardly therefrom as a cantilever.

4. A roof support according to claim 2 wherein said means for applying said pre-load comprises a strut member operatively connected between said carrier means and a part of the roof support olfset downwardly and rearwardly with respect to said carrier means, said strut member including parts which are extensible relatively to each other in a direction longitudinally of said strut to raise and lower said carrier means.

5. A roof support according to claim 1 wherein said auxiliary means comprise an extensible power-operated element interposed operatively between said beam at a position rearwardly of its supporting prop and said first part of said superstructure to control the angular position of said beam in a vertical plane extending longitudinally of the superstructure.

6. A roof support according to claim 5 wherein:

(A) said beam is provided adjacent to its rearward end with laterally projecting arms,

(B) said roof bars of said first part of said superstructure have downwardly presented contact faces overlying said arms,

(C) at least two of said extensible power-operated elements are disposed between said arms and said contact faces to enable the rearward end of the beam to be depressed by extension of said elements, thereby raising the forward end of said beam.

7. A roof support according to claim 1 further comprising guide means operative at the level of Said superstructure and defining a lateral guide path for said beam relative to said channel.

8. A roof support according to claim 7 wherein said guide means comprise guide elements disposed between said beam and said laterally spaced roof bars of said first part of the superstructure at a position rearwardly of the prop which supports said beam.

9. A roof support according to claim 2 wherein said carrier means includes guide means for engaging said beam to control the lateral position thereof at a position forwardly of the supporting prop for said beam.

10. A self advancing roof support for supporting the roof of mine working comprising:

(A) a base,

(B) a plurality of power operated extensible props mounted on said base.

(C) a roof engaging superstructure including:

(i) a first part carried by a plurality of said props at their upper ends and affording a longitudinally extending opening (ii) a second part comprising a beam having its rearward end portion disposed in said opening and its opening forward portion projecting forwardly beyond said base (D) said beam having a downwardly presented longitudinally extending bearing surface disposed above at least one other of said props to enable such prop to support said beam While permitting of longitudinal sliding thereof relatively to such prop and said first part of said superstructure,

(E) traction means for effecting longitudinal movement of said beam relatively to said first part of said superstructure and relatively to said one other of said props supporting said beam.

11. A self advancing roof support according to claim wherein:

(A) an intermediary element is disposed between said downwardly presented bearing surface and said prop situated therebeneath,

(B) said intermediary element is angularly movable relatively to said prop,

(C) said traction means includes a hydraulic ram operatively connected between said intermediary element and said beam.

12. A self advancing roof support according to claim 10 wherein:

(A) an intermediary element is disposed between said downwardly presented bearing surface and said prop situated therebeneath,

(B) said intermediary element has sliding or rolling engagement with said downwardly presented bearing surface in a direction longitudinally thereof,

(C) said traction means is operatively connected between said intermediary elcment and said beam.

13. A roof support according to claim 10 wherein said beam has upwardly presented contact faces at its upper side spaced apart longitudinally of the beam and One at least of which is raised sufficiently above the intervening part of the upwardly presented face of the beam to ensure that the beam bears hollow with respect to the roof.

14. A roof support according to claim 13 wherein one of said contact faces is presented by a pad mounted on the beam adjacent to its forward end.

15. A roof support according to claim 13 wherein said contact faces are presented by forward and rearward end portions of the upwardly presented face of the beam which is concavely curved or bowed as viewed in side elevation with its concave face uppermost.

16. A roof support according to claim 10 wherein said beam comprises laterally spaced longitudinally extending roof bars of box section connected to each other adjacent to their upper sides by a bearing plate providing said downwardly presented longitudinally extending bearing surface, and connected to each other adjacent opposite ends of said bearing plate by cross members extending for substantially the whole depth of each roof bar.

17. A roof support according to claim 10 wherein:

(A) said beam comprises laterally spaced longitudinally extending roof bars connected to each other by transversely extending connecting members,

(B) an intermediary element is disposed between said roof bars and is engaged between said downwardly presented bearing surface and said prop situated therebeneath,

(C) said roof bars laterally inwardly extending flanges projecting beneath said intermediary element to retain same in assembled relation with said beam.

18. A roof support according to claim 11 wherein said beam is further supported by one of said props situated adjacent to the rearward end of said beam, this prop being movable longitudinally with said beam along an elongated seating formed in said base of the support.

19. A self-advancing roof support for supporting the roof of a mine working comprising:

(A) a base,

(B) a plurality of power-operated extensible props mounted on said base,

(C) a roof engaging superstructure including:

(i) a first part carried by a plurality of said props at their upper ends and affording a longitudinally extending opening (ii) a second part comprising a beam having its rearward end portion disposed in said opening and its forward portion projecting forwardly beyond said base (D) said beam having a downwardly presented longitudinally extending bearing surface disposed above at least one other of said props to enable such prop to support said beam while permitting of longitudinal adjustment thereof relatively to such prop and relatively to said first part of said superstructure,

(E) distance determining means operatively connected between said beam and said prop to determine the longitudinal position of said beam relatively to said first part of said superstructure.

20. A roof support according to claim 19 wherein:

(A) an intermediary element is disposed between said downwardly presented bearin surface and said prop situate-d therebeneath,

(B) said intermediatery element and said beam have respective longitudinally spaced attachment members for releasable connection respectively to opposite ends of selectively a hydraulic ram for effecting adjustment of said beam relatively to said first part of said superstructure, or a distance piece for determining the longitudinal position of said beam relatively to said first part of said superstructure.

21. A roof support according to claim 19 wherein:

(A) an intermediary element is disposed between said downwardly presented bearing surface and said prop therebeneath,

(B) said distance determining means comprises a distance piece having means for adjusting the effective length thereof and operatively connected between said intermediary element and said beam.

OTHER REFERENCES German Printed Application 1,179,530, October 1964.

JACOB SHAPIRO, Primary Examiner 

